Evaluation of strained piezoelectric InGaAs/GaAs QW structures grown on (111)B GaAs by photoreflectance spectroscopy

We report the application of photoreflectance (PR) spectroscopy for the evaluation of the interfacial properties of an In_0.17Ga_0.83As/GaAs 10-period multiquantum well (QW) P-I-N structure grown on a(111)B 1°-off towards [2¯11] GaAs substrate by molecular beam epitaxy. From an analysis of the Franz-Keldysh oscillations in the PR spectrum, we determined the electric field in the barriers and, thereby, the piezoelectric field in the wells to properly model the QW potential profile. As the PR spectrum also provides all the confined optical transition energies in the QW, a monolayer (ML) analysis was performed to assess the QW interface abruptness by comparing the experimental transition energies with theoretical calculations for varying well widths. The interface abruptness was determined to be of the order of ±1.5 ML. Therefore, we find no evidence of significant In segregation at the QW interfaces for the growth conditions employed in this work